Accompanying the technology progressing of car industry, more and more intelligent vehicles are developed. A car is facilitated with a plurality of intelligent devices, for example, obstacle detecting device, distance detecting device and etc. A warning signal is emitted appropriately to bring the attention of a driver through these devices in a certain specific state such as being too close to an obstacle or deviating from a car lane and hence, car accidents and damages caused therefore can be reduced substantially. Therefore, more and more car factories stress on the research and development of an intelligent transportation system (ITS) and include it as a standard equipment in a new car.
A traditional obstacle detection apparatus comprises multiple forms, for example, radar type, monocular camera, infrared ray or infrared heat image. As a radar type, infrared line or infrared heat image facility is rather expensive, the required cost is also higher. The research of an image processing is progressing more and more such that adopting a camera to capture images and further assisting follow-up image processing, the obstacle detection can be done; this not only fills the bill on technology but also attains to the consideration of the cost reduction.
However, the current monocular camera image detection system developed up to now still has drawbacks expected to improve; that is the distance estimation error caused by shock or angle change cannot be broken through. For example, a general monocular camera image detection system can only be applied on a smooth road but not on an uphill road, downhill road, crooked road or bumpy road because the serious judgment error might be caused owing to the shock and the angle change.
Therefore, for improving the drawbacks generated from the monocular camera, a double-camera image detection system is proposed. Although, the double-camera image detection system allows a captured image to be more stereo to improve the insufficiency of the monocular camera system, new problems are also arisen. The processing time of the double-camera detection system is double the processing time of the monocular camera detection system such that the time spent on calculation is also double. Thus, when a car is practically driven on a road, because the real-time captured image data amount is too large, the relating information (distance or shape) of a preceding obstacle (person, car or electric pole) cannot be calculated immediately to provide a driver with a warning. Furthermore, the same exposure timings cannot be sure owing to the multiple camera sets of independent formation of image such that specific hardware, e.g. image capturing processing card, is always needed to include between the cameras to allow the exposure timings thereof to be set synchronous or a synchronous camera set is directly adopted. Here, a synchronous resolution is to adopt line segments detection between the same-level zone from a left image to a right image; this is a line to line detection. However, a general low-cost camera cannot attain to the synchronous image capturing such that the left and right image pairs captured by the left and right cameras will also be formed at different heights even if it is the same horizontal line segment. But, the cost of adopting the synchronous cameras or increasing the hardware is always more expansive than a general camera and hence, the whole cost is caused to increase.